The sun is made of primarily hydrogen and helium but contains traces of carbon, oxygen, neon and nitrogen. The sun contains roughly 70 percent hydrogen and around 28 percent helium.
A process called nuclear fusion makes the sun burn hot. During this process, hydrogen is converted to helium. Because of nuclear fusion, each day, there is less hydrogen in the sun and more helium. Eventually, the sun will run out of hydrogen to process, and scientists believe that in around 5 million years, it will use all of its hydrogen and begin to die. During its death, the sun will start to cool and become less bright.